Surgical techniques for support of dental prostheses by means of metallic bone-embedded artificial root fixtures are well known. According to one prior art technique, a titanium bone-embedded implant fixture is interfaced with a metallic abutment post, on which the superstructure is supported. The post has an internally shouldered access bore through which a screw fastener is inserted to actually hold the implant and the post assembled. A number of problems and restrictions are presented however in the attachment of and retention of the superstructures to such abutment posts.
Specifically, the typical superstructures for use with such posts are made of porcelain. The use of a titanium post generally results in a dark, central rod-like shadow, particularly when exposed to high-brightness light, which makes the prosthesis somewhat unattractive and able to be distinguished from a natural tooth. Further, since the materials are different, there are sometimes presented problems with securing of the prosthesis to the support post.
One attempt to solve the attractiveness and securing problems has involved making a support post made entirely of ceramic material, specifically, aluminum oxide. This approach allows direct surface bonding by interaction of a porcelain coping and/or prosthesis to the support post resulting in a secure and almost seamless bond between the prosthetic structure and the support post. While presenting an alternative attraction to the use of a titanium support post, the proposed solution presents a number of previously unanticipated problems.
Ceramic materials generally have a much greater hardness than titanium. When such a support post is used, inevitable rocking of the support post due to, for example, chewing action, causes a high-stress interaction between the metal implant and the ceramic material of the post. Since ceramic is of greater hardness than the titanium implant, it can and does cause damage to the implant. If sufficient damage is caused, eventual surgical intervention is required to remove and replace the titanium implant. In addition, ceramic material is typically not radiopaque. Thus, when examining the juncture between the support post and the titanium implant through conventional dental x-ray imaging, the interface between the two elements is not readily viewable and thus adequate x-ray examination cannot be conducted.